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Visualization and Measurement of Velocity Fields by Means Optical Discrimination of the Doppler Frequency Shift of the Scattered Light

Dubnishchev, Yu. N. und Belousov, P. P. und Belousov, P. Ya. und Kompenhans, Jürgen und Chugui, Yu. N. (2008) Visualization and Measurement of Velocity Fields by Means Optical Discrimination of the Doppler Frequency Shift of the Scattered Light. 13th International Symposium on Flow Visualization, 2008-07-01 - 2008-07-04, Nice (France).

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Kurzfassung

At Doppler Global Velocimetry (DGV) the frequency of the Doppler shifted light scattered from the fluid has to be determined to obtain the velocity field. Standard DGV is based on the principle of transforming the Doppler shifted frequency into variations of grey levels by means of an Iodine cell, the transmittance of which is frequency dependent. Standard DGV configurations require a second reference camera to monitor the flow field. The major problems of the Standard DGV technique at present are limitations of the velocity resolution at low flow velocities and the influence of multi–particle scattering on the results of the velocity measurements. This paper will discuss different solutions to overcome these problems. First, a method of optical discrimination of the Doppler frequency shift has been realized in an optical Doppler processor (ODP) with coherent feedback. This processor is used as a converter frequency ==> intensity. One implementation of the Optical Doppler Processor consists of a semi–confocal interferometer as wide–band spatial frequency filter with resonant transfer function. The slope of its resonance transfer function is used as frequency discrimination curve. The ODP is included in a feed back loop with the laser. In the German Aerospace Center (DLR) in Göttingen joint experiments on visualization and measurement of velocity fields in gas jets from a test nozzle in the regime of low velocities of a few meters/second have been made utilizing the ODP. A method to eliminate the influence of multi–particle scattering on the result of the measurement of velocity fields based on linear operations with frequency–demodulated images of the flow, formed in various areas of the angular spectrum of the scattered light, is proposed. The registration of the image can be made by only one CCD camera without the need of a second camera for a reference image. Eliminating the influence of multi–particle scattering is subject of an application for an European patent.

elib-URL des Eintrags:https://elib.dlr.de/52167/
Dokumentart:Konferenzbeitrag (Vortrag, Paper)
Titel:Visualization and Measurement of Velocity Fields by Means Optical Discrimination of the Doppler Frequency Shift of the Scattered Light
Autoren:
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID-iDORCID Put Code
Dubnishchev, Yu. N.Institute of Thermophysics, Siberian Branch of the Russian Academy of SciencesNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Belousov, P. P.Institute of Thermophysics, Siberian Branch of the Russian Academy of SciencesNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Belousov, P. Ya.Institute of Thermophysics, Siberian Branch of the Russian Academy of SciencesNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Kompenhans, JürgenNICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Chugui, Yu. N.Technological Design Institute of Scientific Instrument Engineering of SB RASNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Datum:2008
Referierte Publikation:Nein
Open Access:Nein
Gold Open Access:Nein
In SCOPUS:Nein
In ISI Web of Science:Nein
Name der Reihe:CD-ROM Conference Proceedings
Status:veröffentlicht
Stichwörter:Doppler Global Velocimetry (DGV), Optical Doppler Processor, multi–particle scattering
Veranstaltungstitel:13th International Symposium on Flow Visualization
Veranstaltungsort:Nice (France)
Veranstaltungsart:internationale Konferenz
Veranstaltungsdatum:2008-07-01 - 2008-07-04
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Luftfahrt
HGF - Programmthema:Starrflügler (alt)
DLR - Schwerpunkt:Luftfahrt
DLR - Forschungsgebiet:L AR - Starrflüglerforschung
DLR - Teilgebiet (Projekt, Vorhaben):L - Flugphysik (alt)
Standort: Göttingen
Institute & Einrichtungen:Institut für Aerodynamik und Strömungstechnik > Experimentelle Verfahren
Hinterlegt von: Micknaus, Ilka
Hinterlegt am:30 Jul 2008
Letzte Änderung:27 Apr 2009 14:32

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